Carol of Calamity

People always say that it's in the darker swirls of the city where the interesting people live and breathe and skip- However, Sangwoo knew better than that. In his pristine office building, with different fractures of pompous married wives and classy gentlemen, was where he had the most fun.
Nobody ever needs to go into the alleyways to find evil, a majority of the time it's right in front of them.

They just need to look closely enough.

I.e. The one where Yoonbum is Sangwoo's assistant and things only go downhill from there.